<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <div id="root"></div>

    <script src="https://unpkg.zhimg.com/react@17.0.2/umd/react.development.js"></script>
    <script src="https://unpkg.zhimg.com/react-dom@17.0.2/umd/react-dom.development.js"></script>
    <script src="https://unpkg.zhimg.com/@babel/standalone/babel.min.js"></script>
    <script type="text/babel">
        class Login extends React.Component {

            state = {
                username: '',
                password: ''
            }
           
            handleSubmit = (event) => {
                // 阻止默认行为 
                event.preventDefault()

                const {username, password} = this.state
                console.log('username: ', username, ', password: ', password)
            }

            userNameChange = event => {
                this.setState({
                    username: event.target.value
                })
            }

            passwordChange = eventt => {
                this.setState({
                    password: event.target.value
                })
            }

            render() {
                return (
                    <form onSubmit={this.handleSubmit}>
                        <div>
                            <label>用户名：</label>
                            <input type="text" name="username" onChange={this.userNameChange} />
                        </div>
                        <div>
                            <label>密　码：</label>
                            <input type="password" name="password" onChange={this.passwordChange} />
                        </div>
                        <div>
                            <button>登录</button>
                        </div>
                    </form>
                )
            }
        }

        ReactDOM.render(<Login />, document.getElementById('root'))
    </script>
</body>
</html>